Resource Management for Dynamic Service Chain Adaptation
draft-lee-nfvrg-resource-management-service-chain-00
The information below is for an old version of the document.
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|---|---|---|---|
| Authors | Seungik Lee , Sangheon Pack , Myung-Ki Shin , EunKyoung Paik | ||
| Last updated | 2014-10-24 | ||
| Replaced by | draft-irtf-nfvrg-resource-management-service-chain, draft-irtf-nfvrg-resource-management-service-chain | ||
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draft-lee-nfvrg-resource-management-service-chain-00
Internet Research Task Force (IRTF) S. Lee
Internet-Draft ETRI
Intended status: Informational S. Pack
Expires: April 26, 2015 KU
M-K. Shin
ETRI
E. Paik
KT
October 23, 2014
Resource Management for Dynamic Service Chain Adaptation
draft-lee-nfvrg-resource-management-service-chain-00
Abstract
This document specifies problem definition and use cases of dynamic
service chain adaptation for traffic optimization, failover, load
balancing, etc. It further describes design considerations and
relevant framework for the resource management capability that
dynamically creates and updates network forwarding paths (NFPs)
considering resource state of VNF instances.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on April 26, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
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publication of this document. Please review these documents
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Dynamic service chain adaptation . . . . . . . . . . . . . . 4
3.1. Use cases . . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Design considerations . . . . . . . . . . . . . . . . . . 6
3.3. Framework . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Related works in IETF SFC WG . . . . . . . . . . . . . . . . 7
5. Security Considerations . . . . . . . . . . . . . . . . . . . 7
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Network Functions Virtualisation (NFV) [ETSI-NFV-WHITE] offers a new
way to design, deploy and manage network services. The network
service can be composed of one or more network functions and NFV
relocates the network functions from dedicated hardware appliances to
generic servers, so they can run in software. Using these
virtualized network functions (VNFs), the network service can be
described by a service chain (or VNF forwarding graph; VNF-FG) which
defines an ordered sequence of VNFs for the composed service. The
VNF-FG can be instantiated by creating or selecting VNF instances and
virtual links (VLs) among them, which results in a network forwarding
path (NFP).
The performance or state of the NFP depends on the ones of VNF
instances and underlying NFVI resources. For example, if one of the
VNF instances in a NFP gets failed, the whole network service using
the NFP also gets failed. Thus, the VNF instances per NFP need to be
carefully selected at VNF-FG instantiation or dynamically replaced by
other VNF instances at run-time for better performance and
resilience.
This document specifies problem definition and use cases for dynamic
service chain adaptation for traffic optimization, failover, load
balancing, etc. It further describes design considerations and
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relevant framework for the resource management capability that
dynamically creates and updates NFPs considering resource state of
VNF instances.
This document mainly focuses on the resource capability in the ETSI
NFV framework [ETSI-NFV-ARCH] but also studies its applicability to
the control plane of SFC architecture [I-D.ietf-sfc-architecture].
2. Terminology
This document uses the following terms and most of them were
reproduced from [ETSI-NFV-TERM].
o Network Functions (NF): A functional building block within a
network infrastructure, which has well-defined external interfaces
and a well-defined functional behavior.
o Network service: A composition of network functions and defined by
its functional and behavioural specification.
o NFV Framework: The totality of all entities, reference points,
information models and other constructs defined by the
specifications published by the ETSI ISG NFV.
o Virtualised Network Function (VNF): An implementation of an NF
that can be deployed on a Network Function Virtualisation
Infrastructure (NFVI).
o NFV Infrastructure (NFVI): The NFV-Infrastructure is the totality
of all hardware and software components which build up the
environment in which VNFs are deployed.
o NF Forwarding Graph: A graph of logical links connecting NF nodes
for the purpose of describing traffic flow between these network
functions.
o VNF Forwarding Graph (VNF-FG): A NF forwarding graph where at
least one node is a VNF.
o Virtual Link: A set of connection points along with the
connectivity relationship between them and any associated target
performance metrics (e.g. bandwidth, latency, QoS). The Virtual
Link can interconnect two or more entities (VNF components, VNFs,
or PNFs).
o Scaling: Ability to dynamically extend/reduce resources granted to
the Virtual Network Function (VNF) as needed.
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3. Dynamic service chain adaptation
The goal of dynamic service chain adaptation is to optimize the
performance of network services. To meet this goal, NFPs of the
network services need to consider the state of NFV resources (such as
VNF instances or virtual links) at construction. The NFPs also need
to dynamically adapt to the changes of the resource state at run-
time, such as availability, load, and topological locations of VNF
instances. The adaptation of NFPs can be executed by monitoring the
resource state of VNF instances and VLs and replacing the original
VNF instances of the NFP with new VNF instances that constitute a NFP
with better performance. This functionality can be a part of
Orchestrator functional building block in the NFV framework
[ETSI-NFV-MANO] but it needs further study.
3.1. Use cases
There are several use cases of dynamic service chain adaptation:
fail-over, end-to-end service optimization, traffic optimization,
load balancing, energy efficiency, and so on.
Fail-over
When one of VNF instances in a NFP gets failed to run due to failure
of its VM or underlying network, the whole chain of network service
also gets failed. For service continuity, the failure of VNF
instance needs to be detected and the failed one needs to be replaced
with the other one which is available to use. Figure 1 presents an
example of the fail-over use case. A network service is defined as a
chain of VNF-A and VNF-B; and the service chain is instantiated with
VNF-A1 and VNF-B1 which are instances of VNF-A and VNF-B
respectively. In the meantime, failure of VNF-B1 is detected so that
VNF-B2 replaces the failed one for fail-over of the NFP.
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+--------+ +--------+
| VNF-B2 | #| VNF-B2 |###
+--------+ +--------+ +--------+ # +--------+
###| VNF-A1 | _|_ ###| VNF-A1 |# _|_
+--------+ (___) +--------+ (___)
___/ # / \ \ ___/ / \
(___)+---#------+ + ===} (___)+----------+ +
# \ ___ / / \ ___ /
# (___) (___)
# | |
# +--------+ +--------+
######| VNF-B1 |### (failure)--> | VNF-B1 |
+--------+ +--------+
### NFP
Figure 1: A fail-over use case
End-to-end service optimization
Traffic for a network service traverses all of the VNF instances
given by a NFP before reaching a target end point. Thus, stretch of
the traffic route along a NFP may vary according to topological
locations of VNF instances and such stretch needs to be kept low to
make topological distance of two end points of the network service
short. This stretch can be managed by constructing or adapting the
NFP considering topological locations of the VNF instances.
Traffic optimization
A network operator may provide multiple network services with
different VNF-FGs and different flows of traffic traverse between
source and destination end-points along the VNF-FGs. For efficiency
of network management resource usage, the NFPs need to be built as to
localize the traffic flows or as to avoid bottleneck links shared by
multiple traffic flows. In this case, multiple NFV instances of
different NFPs need to be considered together at constructing a new
NFP or adapting one.
Load balancing
A single VNF instances may be shared by multiple traffic flows of the
same of different network services. In order to avoid bottleneck
points due to overloaded NFV instances, NFPs need to be constructed
or maintained to distribute workloads of the shared VNF instances.
Energy efficiency
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Energy efficiency in the network is getting important to reduce
impact on the environment so that energy consumption of VNF instances
using VNFI resources (e.g., compute, storage, I/O) needs to be
considered at NFP construction or adaptation. For example, a NFP can
be constructed as to make traffic flows aggregated into a limited
number of VNF instances as much as its performance is preserved in a
certain level.
3.2. Design considerations
To support the aforementioned use cases, it is required to support
resource management capability which provides service chain (or NFP)
construction and adaptation by considering resource state or
attributes of VNF instances and virtual links among them. The
resource management operations for service chain construction and
adaptation can be divided into several sub-actions:
o Select a VNF instance
o Evaluate a VNF instance and a virtual link
o Replace a VNF instance to update a NFP
o Monitor attributes of a VNF instance and a virtual link
o Migrate a VNF instance to a different topological location
Note: While scaling-in/out or -up/down of VNF instances is an
essential action for NFV resource management, sub-actions with
scaling for service chain adaptation are still under study.
As listed above, VNF instances are selected or replaced according to
monitoring or evaluation results of performance metrics of the VNF
instances and virtual links. Studies about evaluation methodologies
and performance metrics for VNF instances and NFVI resources can be
found at [ETSI-NFV-PER001] [I-D.liu-bmwg-virtual-network-benchmark]
[I-D.morton-bmwg-virtual-net]. The performance metrics of VNF
instances and virtual links specific to service chain construction
and adaptation can be defined as follows:
o availability (or failure) of a VNF instance and a virtual link
o a topological location of a VNF instance
o a utilization rate of a VNF instance
o a throughput of a VNF instance
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o energy consumption of VNF instance
o bandwidth of a virtual link
o latency of a virtual link
3.3. Framework
The resource management functionality for dynamic service chain
adaptation takes role of NFV orchestration with support of VNF
manager and Virtualised Infrastructure Manager (VIM) in the NFV
framework [ETSI-NFV-ARCH]. Detailed functional building block and
interfaces are still under study.
4. Related works in IETF SFC WG
IETF SFC WG provides a new service deployment model that delivers the
traffic along the predefined logical paths of service functions
(SFs), called service function chains (SFCs) with no regard of
network topologies or transport mechanisms. Basic concept of the
service function chaining is similar to VNF-FG where a network
service is composed of SFs and deployed by making traffic flows
traversed instances of the SFs in a pre-defined order.
There are several works in progress in IETF SFC WG for resource
management of service chaining. [I-D.ietf-sfc-architecture] defines
SFC control plane that selects specific SFs for a requested SFC,
either statically or dynamically but details are currently outside
the scope of the document. There are other works
[I-D.ww-sfc-control-plane] [I-D.lee-sfc-dynamic-instantiation]
[I-D.krishnan-sfc-oam-req-framework] [I-D.aldrin-sfc-oam-framework]
which define the control plane functionality for service function
chain construction and adaptation but details are still under study.
While [I-D.dunbar-sfc-fun-instances-restoration] and
[I-D.meng-sfc-chain-redundancy] provide detailed mechanisms of
service chain adaptation, they focus only on resilience or fail-over
of service function chains.
5. Security Considerations
TBD.
6. IANA Considerations
TBD.
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7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
7.2. Informative References
[ETSI-NFV-ARCH]
ETSI, "ETSI NFV Architectural Framework v1.1.1", October
2013.
[ETSI-NFV-MANO]
ETSI, "Network Function Virtualization (NFV) Management
and Orchestration V0.6.3", October 2014.
[ETSI-NFV-PER001]
ETSI, "Network Function Virtualization: Performance and
Portability Best Practices v1.1.1", June 2014.
[ETSI-NFV-TERM]
ETSI, "NFV Terminology for Main Concepts in NFV", October
2013.
[ETSI-NFV-WHITE]
ETSI, "NFV Whitepaper 2", October 2013.
[I-D.aldrin-sfc-oam-framework]
Aldrin, S., Pignataro, C., and N. Akiya, "Service Function
Chaining Operations, Administration and Maintenance
Framework", draft-aldrin-sfc-oam-framework-00 (work in
progress), July 2014.
[I-D.dunbar-sfc-fun-instances-restoration]
Dunbar, L. and A. Malis, "Framework for Service Function
Instances Restoration", draft-dunbar-sfc-fun-instances-
restoration-00 (work in progress), April 2014.
[I-D.ietf-sfc-architecture]
Halpern, J. and C. Pignataro, "Service Function Chaining
(SFC) Architecture", draft-ietf-sfc-architecture-02 (work
in progress), September 2014.
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[I-D.krishnan-sfc-oam-req-framework]
ramki, r., Ghanwani, A., Gutierrez, P., Lopez, D.,
Halpern, J., Kini, S., and A. Reid, "SFC OAM Requirements
and Framework", draft-krishnan-sfc-oam-req-framework-00
(work in progress), July 2014.
[I-D.lee-sfc-dynamic-instantiation]
Lee, S. and M. Shin, "SFC dynamic instantiation", draft-
lee-sfc-dynamic-instantiation-00 (work in progress), July
2014.
[I-D.liu-bmwg-virtual-network-benchmark]
Liu, V., Liu, D., Mandeville, B., Hickman, B., and G.
Zhang, "Benchmarking Methodology for Virtualization
Network Performance", draft-liu-bmwg-virtual-network-
benchmark-00 (work in progress), July 2014.
[I-D.meng-sfc-chain-redundancy]
Meng, W. and C. Wang, "Redundancy Mechanism for Service
Function Chains", draft-meng-sfc-chain-redundancy-00 (work
in progress), July 2014.
[I-D.morton-bmwg-virtual-net]
Morton, A., "Considerations for Benchmarking Virtual
Network Functions and Their Infrastructure", draft-morton-
bmwg-virtual-net-01 (work in progress), July 2014.
[I-D.ww-sfc-control-plane]
Li, H., Wu, Q., Boucadair, M., Jacquenet, C., and W.
Haeffner, "Service Function Chaining (SFC) Control Plane
Achitecture", draft-ww-sfc-control-plane-03 (work in
progress), September 2014.
Authors' Addresses
Seung-Ik Lee
ETRI
218 Gajeong-ro Yuseung-Gu
Daejeon 305-700
Korea
Phone: +82 42 860 1483
Email: seungiklee@etri.re.kr
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Sangheon Pack
Korea University
145 Anam-ro, Seongbuk-gu
Seoul 136-701
Korea
Phone: +82 2 3290 4825
Email: shpack@etri.re.kr
Myung-Ki Shin
ETRI
218 Gajeong-ro Yuseung-Gu
Daejeon 305-700
Korea
Phone: +82 42 860 4847
Email: mkshin@etri.re.kr
EunKyoung Paik
KT
17 Woomyeon-dong, Seocho-gu
Seoul 137-792
Korea
Phone: +82 2 526 5233
Email: eun.paik@kt.com
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